1. Field of the Invention
The present invention relates to a device for stabilizing boats, in particular yachts.
2. Discussion of the Related Art
Boats in general and yachts in particular are subject to the force of wind and waves. These wave actions cause a boat to roll, pitch and yaw in an unpleasant manner. This creates an unpleasant sensation for a person who does not spend a significant time on a boat. The sensation may be so extreme as to cause a condition known as seasickness. These unpleasant forces effect the yacht and passengers at all times, underway and at rest.
Boat movement, relative to its level position, is measured in terms of pitch (movement along the axis line from bow to the stern), roll (movement along the axis line from the port side to the starboard side), and yaw (a rotational heading movement along the center point of the boat).
There are a number of ways to reduce vessel movement. A solution is to build a larger vessel, which is usually not an economical solution in most cases. Another approach is to only use the vessel during calm seas, although this is impractical for vessels that must be used on a daily, commercial basis.
Active control systems have been developed to reduce the problem of vessel roll only. One such device is disclosed in U.S. Pat. No. 4,487,152 to Larson which illustrates the use of an air foil-shaped stabilizer above the propeller to induce a lift at the stern portion of the boat.
An attitude control device in the form of a wing or vane is also disclosed in U.S. Pat. No. 3,980,035 to Johansson which shows the vane positioned in the slip stream behind the propeller.
Other developments involve forming the anti-cavitation plate with an inclined lower surface to preclude formation of low pressure areas into which air or exhaust gases can be sucked, and to exert a lift at the stern of the boat. A deflector has also been developed to create a high pressure area at the trailing edge of the anti-cavitation plate to improve trim tab effectiveness by forestalling the passage of air into the area of the trim tab, such as the device disclosed by Holterman in U.S. Pat. No. 3,955,527.
U.S. Pat. No. 4,708,672 to Bentz a boat stabilization systems uses an adjustable wedge-shaped member formed on an adjustably mounted trim tab located on the underside of an anti-cavitation plate of an outboard motor. The wedge-shaped member tends to have a downwardly inclined lower surface extending generally laterally from and perpendicularly to a fin-shaped member of the trim tab. Movement of the boat through the water imparts a force against the downwardly inclined surface to effect a generally vertical torque on the boat substantially eliminating proposing of the boat in a given speed range.
U.S. Pat. No. 4,968,275 to Carlson a stabilizer is attached to the cavitation plate on the leg of a motor boat motor. Two elongated tubular members are attached by mounting brackets to the motor's cavitation plate. The tubular members are attached at a downward angle away from the boat so that an upward force is created by the hydrodynamic jet action of water flowing through the tubular members at the rear of the boat when the boat moves in a forward direction. The upward jet created force at the rear of the boat keeps the boat horizontal and stable at high speeds.
U.S. Pat. No. 4,995,840 to Seale, et al the describes a stabilizing fin for a motor boat which is of a generally triangular shape, and the fin is attached to the mounting side with a longitudinally extending slot for mounting on a cavitation plate on a motor post of an outboard motor. Suitable means are also provided for removably securing the fin to the cavitation plate.
U.S. Pat. No. 5,048,449 to Templeman describes a stabilizing system that has the first and second arm portions that are removably attached. The first and second arms together and selectively movable toward and away from each other for varying the width of the slot. The ability to vary the width of the slot for receiving the drive unit allows the stabilizer to be adjusted to fit virtually any conventional outboard or inboard/outboard boat motor.
U.S. Pat. No. 5,144,904 to Weldon describes a stabilization system when the boat was not in motion. The apparatus for stabilizing boats is comprised of a weighted concave body which is suspended from the boat and which is formed as a grid defining openings through the body and a flexible flap in the concavity of the body, the flap blocking the openings when the body rises in the water due to rolling of the boat so as to inhibit rolling and the flap moving away from the openings to permit the apparatus to rapidly fall as the boat rolls in the opposite direction.
U.S. Pat. No. 5,848,922 to Itima, et al. describes a stabilization system that attaches above the propeller. It is a hydrofoil stabilizer for a marine motor that includes a hydrofoil wing having a generally planar configuration and a shroud member affixed to an underside of the hydrofoil wing.
U.S. Pat. No. 6,973,847 to Adams uses a gyroscopic roll stabilizer for control of the boat. The stabilizer includes a flywheel, a flywheel drive motor configured to spin the flywheel about a spin axis, an enclosure surrounding a portion or all of the flywheel and maintaining a below-ambient pressure or containing a below-ambient density gas, a gimbal structure configured to permit flywheel precession about a gimbal axis, and a device for applying a torque to the flywheel about the gimbal axis. The flywheel, enclosure, and gimbal structure are configured so that when installed in the boat the stabilizer damps roll motion of the boat. Preferably, the flywheel drive motor spins the flywheel at high tip speeds.
Commercially available stabilizers with varied designs are manufactured by Koopnautic (www.koopnautic.com)